Reaction of ethylenimines with thiols and product thereof



REACTION 1F ET I PRUDUCT THEREOF No Drawing. Application August 3, 1939, Serial No. 2883M.

13 Claims.

This invention relates to organic compounds and more particularly to organic sulfides containing an amino group and still more particularly to beta-aminoethyl sulfides.

This invention has as an object the provision of a new and convenient process for the preparation of beta-aminoethyl sulfides. Another object is the provision of a process for the preparation of new compounds having a plurality of beta-aminoethylthio groups. A further object is the new class of compounds having a plurality of betaaminoethylthio groups. Another object is the provision of a process for making anti-corrosion and anti-sludge agents for lubricating oils. Other objects will appear hereinafter.

These objects are accomplished by the following invention wherein an ethylenimine is reacted, under substantially neutral conditions, with a thiol, free from groups, other than thiol, which react With ethylenimines. A preferred modification of the invention is that wherein the thiol contains a plurality of thiol groups. Another phase of the invention is the class of poly-betaaminoethylthio substituted compounds prepared by the preferred process modification.

In the process of this invention, substantially cquimolecular amounts of a thiol and of an ethylenimine are reacted under substantially neutral conditions, at a temperature and for a period of tim sufiicient to brin about substantially complete reaction. The reaction product is then freed from unchanged reactants, if any are prescut, and purified by suitable procedures. By substantially neutral conditions is meant that the reaction mixture has an acidity corresponding to that of a mixture containing th free thiol and containing no acidic material other than the thiol. The acidic nature of the thiol is low as is indicated inter alia by the article by Schwarzenbach and Epprecht, Helv. Chem. Acta. 19, 169 (1936).

Although the invention is not to be limited by the following theoretical explanation, it is probable that, under the slightly acidic influence of the mercapto group, the rather unstable ethylenimine ring is opened, with subsequent addition of the thiol to the radical thus formed. The not result of the reaction is represented by the equation:

rusn+om-orn --i n'somornNnIu or, when a polythiol is used:

R'(SH),+IGH-zCHi n'rsoniomNnno.

The reaction products, which are generically EXAMPLE I Beta-aminoethylthiopropane A mixture of 17.2 parts of ethylenimine and 30.4 parts of n-propanethiol is heated in a closed vessel at 100 C. for 20 hours. The reaction product is then subjected to distillation, whereupon a small amount of unchanged starting materials is first removed, then 37 parts of a homogeneous liquid boiling at 84-87 C. at 23 mm. pressure is obtained. This product, a colorless oil, boils on redistillation at 85-86 C. at 25 mm. pressure. Other physical constants are: r1 0.9295; N 1.4.831. Analyses indicate that it is beta-aminoethylthiopropane, CH3CH2CH2SCH2CH2NH2.

Calcd. for C5H13NS: 8%, 26.89. Found: 26.82, 26.87. Neutralization equivalent (with N/l0 HCl in the presence of methyl orange): calcd. 119;

found, 119.5.

The yield in beta-aminoethylthiopropane is 78% of the theory. The product is soluble in water and organic solvents such as methanol and benzene.

EXAMPLE II 1,6-bis-(beta-aminoethylthio) hexane A mixture of 11 parts of ethylenimine and 18 parts of hexane-1,6-dithiol is heated in a closed vessel, without solvent or added catalyst, at C. for 23 hours. There is obtained, on distillation of the reaction product, 25 parts of an oil boiling around 200 C. at 6 mm. pressure. The

product, onredistillation in an atmosphere of Calcd. for CxoHaiNaSs: C, 50.85; H, 10.17; S,

27.12. Found: C, 51.02; H, 10.04; S, 26.74. Neutralization equivalent (with N/IO HG]. in the presence of methyl orange): calcd. 236; found 241.

The yield in Lil-bis-(beta-aminoethylthlo)- hexane is 89% oi the theory. The product is soluble in Water and the common organic solvents.

In the process of the present invention, any thlol free from functional groups, other than thiol, which are capable of reacting with ethyleniminee substantially faster than the thiol group, may be used. Examples of such undesired functional groups are the carbonyl, sulfonyl, active halogen, aldehyde, acid chloride group, etc. When such a functional roup is present, the reaction product will in general be nonhomogeneous and polymeric in character. The invention is applicable to thiols of the formula R'(SH)x, wherein R is an organic radical ol valence :c, a being an integer and at least one, said organic radical being free from the undesirable functional groups above indicated. In the preferred subgenus, R. is a hydrocarbon radical of valence a. It may therefore be allryl, cycloallml, aryl or arallryl, and may be saturated or unsaturated, e. a, it may be methyl, ethyl, isopropyl, allyl, butyl, isohutyl, crotyl, hexyl, octyl, decyl, octadecyl, cyclopentyl, cycioheiryl, phenyl, tolyl naphthyl, tetrahydronaphthyl, benzyl, phenylethyl, ethylene, trimethylene, tetrameth ylene, decamethylene, m-phenylene, oand pitylylene. R may also contain a hetero atom Within the hydrocarbon chain, that is, It may he heteroaliphatlc or heterocycllc, e. an, ethomethyl, GHsCHaU, proporryethyl,

QHaCHaOmHr (thioethyl) ethyl, -CH2CH2SC2H5, methyl sill iidc, CHrCEhBCHsCHadiethyl cuddle,

thlenyl, pyrrolyl, pyrldyl, pipericlyl, uulnolyl, etc. llhe invention is generic to the use oi ethyl, enlmlnes, i. e., ethylenimine CHy-GHS t 3 and its hydrocarbon substitution products, e, on, those wherein the hydrogen on the nitrogen is replaced by methyl, ethyl, propyl, butyl, lsobutyl, hexyl, decyl, dodecyl, hesadecyl, cycloheml, phenyl, benzyl, etc, and those wherein one or more hydrogens attached to the ethylenimlne carbon are replaced by methyl, ethyl, butyl, herwl, doclecyl, octadecyl, cyclohenyl, phenyl, etc. radicals. In the claims, when the term "an ethylenimine is used, it is to he understood as including not only ethylenlmine but also its by drocarbon substitution products. The term ethylenimine in the singular without the indefinite article is meant to include only ethylenhmine one-on,

which lathe greatly preferred species, ovrll I its ready availability and ease oi reaction.

The reaction temperature may be varied slightly elevated temperature (e. 1;. 50 E.) to high temperature (e. 2% 13.), thereaction tilncbeing, of course, reduced at th'c'jrnore ele rated temperatures. Obviously, the teinperature must be chosen so as to avoid decomposition of the starting materials or end product. In gen-- eral, a temperature between 100 C. and 150 C. will be sufilcient to bring about substantially acct-pas complete reaction in a period of from t to 241 hours.

The reaction may be carried out either at at mospheric pressure or at superatmospheric pressure (in a closed vessel). The latter conditions are desirable when either the thlol or the ethylenlmine or both are low boiling, in which case the reaction temperature in an open vessel would of necessity be low, with consequent increase of reaction time, and possibility of loss of reactants through evaporation. The pressure developed during the reaction will, of course, depend on the volatility of the reactants and on the temperature oi the reaction, and the material or which the reactor is built will have to be chosen accordingly. When both reactants are sulficiently high boiling, the reaction may conveniently be carried out in an open vessel, with suitable provision for returning the condensed vapors to the reaction mixture.

The presence of a solvent is not necessary to the conduct of the operation. However, a solvent may be desirable in. certain cases, for example, when the thiol to be reacted is a high melting solid. Any solvent which is inert towards both the thiol and the ethylenimine under the conditions of the reacti n may be used, for example,

- aliphatic, cyoloaliphatic, and aromatic hydrocarall bons, ethers such as dl-n-butyl ether, or cyclic others such as dioxane.

In general, catalysts are unnecessary the reaction proceeds without a catalyst at appropriate temperature with sufficient speed. acidic and basic materials used as catalysts in other reactions are in general to be avoided because, by catalyzing undesired side reactions, they do crease the yield and increase the difiicultics oi preparation. Thus, herradecanthiol and ethylenlmine in the presence of aqueous sodium luvdroizide yield an apparently polymeric material oi" indefinite composition. Acidic conditions tend to polymerize the ethylenlmine so that acidic catalysts are to be avoided.

The reaction products, 1. e., the beta-aminoethyl sulfides, may be readily isolated and purlbed by the welldmovvn methods which include, according to expediency, distillation, preferably under reduced pressure, crystallisation, from solution or from a melt, steam distillation, etc. there is, in general, no difficulty in isolating the desired product in good yield, since little or no lay-product or elimination product is formed in the process of this invention. I any cases the product may be used as such, zoout any purification.

It la, in general, advantageous to use the re actants (thiol and the-ethylenimine) in molecular proportions, that is, one moi-oi the ethylenirnine for each inercapto group. However, it desired, an excess of either reactant may be used. For example, it may be advantageous to use an excess of the more volatile, or of the cheaper, reactant if the reaction is carried out at atmospheric pressure.

The hetanuh'iooethyl sulfides produced according to the process of this invention are ticularly valuable as anti-corroslori and sludge agents in lubricating oils. They are alsr of great interest as starting materials in chemical syntheses, owing toihe reactivity of thl amino group. In these applications, the poly- (bete-aminoethyl) sulfides obtainable by the process of this invention are of particular interest In lubricating oil stabilizers of the beta-amino ethyl sulfide type, it is believed that the groin -SCH2CH2NH2 is responsible for the activity of the molecule as a whole. It is therefore advantageous to have more than one such group in the molecule. From another standpoint, and also by reason of their poly-functional character, the poly-(beta-aminoethyl)sulfides are useful ingredients in condensation and addition reactions, yielding valuable high molecular weight polymeric materials.

This invention is of advantage in making readily available certain hitherto dimcultly obtainable beta-aminoethyl sulfides. A convenient route to the beta-aminoethyl sulfides is opened by this invention. The process herein disclosed is particularly easy to carry out, requiring no special or expensive equipment and a minimum of attention. It is further extremely advantageous in that no by-product is eliminated or evolved, thereby insuring easy isolation and purification of the final product. It is of further advantage in providing a means for the preparation of a new class of compounds hitherto unavailable, i. e., amine sulfides having a plurality of betaaminoethylthio groups.

The above description and examples are intended to be illustrative only. Any modification of or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.

What is claimed is:

1. 1,6-bis(beta-aminoethylthio) hexane.

2. The process which comprises reacting, under 200 C. under substantially neutral conditions an ethylenimine and a thiol free from groups, other than thiol, reactive with the ethylenimine.

3. The process which comprises reacting at 50- 200 C. under substantially neutral condition an ethylenimine and a thiol wherein the non-thiol portion of the molecule is selected from the class consisting of hydrocarbon radicals and hydrocarbon radicals containing a hetero atom in the carbon chain.

4. The process which comprises reacting at 50- 200 C. under substantially neutral conditions an ethylenimine and a polythiol wherein the nonthiol portion of the molecule is selected from the class consisting of hydrocarbon radicals and hydrocarbon radicals containing a hetero atom in the carbon chain.

5. The process which comprises reacting at 200 C. under substantially neutral conditions ethylenimine and a thiol wherein the non-thiol portion of the molecule is selected from the class consisting of hydrocarbon radicals and hydrocarbon radicals containing a hetero atom in the carbon chain.

6. The process which comprises reacting at 50- 200 C. under substantially neutral conditions ethylenimine and a polythiol wherein the nonthiol portion of the molecule is selected from the class consisting of hydrocarbon radicals and hydrocarbon radicals containing a hetero atom in the carbon chain.

7. A process comprising reacting under substantially neutral conditions at 50-200 C. a thiol R(SH)1, wherein R is a hydrocarbon radical of valence a: and a: is an integer at least equal to 1, with an ethylenimine CH:-CH:

wherein R is a member of the class consisting of hydrogen and hydrocarbon radicals.

8. Process which comprises reacting, under substantially neutral conditions at 50-200 C., an ethylenimine with an alkanethiol.

9. Process which comprises reacting, under substantially neutral conditions at 50-200 C., ethylenimine with an alkanethiol.

10. Process which comprises reacting, under substantially neutral conditions at 50-200 C., an ethylenimine with an alkanepolythiol.

11. Process which comprises reacting, under substantially neutral conditions at 50-200 0., ethylenimine with an alkanepolythiol.

12. Process which comprises reacting ethylenimine with n-propanethiol under substantially neutral conditions at 50-200 C.

13. Process which comprises reacting ethylenimine .with hexan-1,6-dithiol under substantially neutral conditions at 50-200 C.

GERARD JEAN BERCHET. 

